Interesting, I can see how it can increase air capacity and compression ratio. And valve bounce should be a thing of the past. However there may be a weight issue also rotational mass maybe a problem. Its difficult to gauge the size of the valves (pistons) would we be reverting to 2 valves (pistons) per cylinder? A 4 valve (pistons) per pot would be quite complex.

Interesting idea, replacing the valves with pistons that can then participate in the charge compression. The improved flow because the inlet/outlet ports are relatively unimpeded should give improved power too.

However, first glimpse drawbacks are: - relative inlet and exhaust 'piston' timing cannot be varied as they run from the same overhead crank. - engine design looks pretty heavy with the crank/piston mechanism at the top. - expensive cylinder head, with honed piston bores, a crank, con-rods and pistons. - the exhaust 'piston' will see high temperatures and will require clever design to avoid conducted heat cooking all the oil in the rings. - pistons working downwards will have gravity working against them as far as bore oil control is concerned. Without some pretty clever design, you'd get more oil down the bore than you do down a valve guide that is easily sealed with a stem seal. Hydrocarbon emissions might therefore be a challenge.

- pistons working downwards will have gravity working against them as far as bore oil control is concerned. Without some pretty clever design, you'd get more oil down the bore than you do down a valve guide that is easily sealed with a stem seal. Hydrocarbon emissions might therefore be a challenge.

I await further developments with interest (if they happen!).

>> Edited by nel on Monday 21st February 10:20

Fliping it on its side like an old VW, Porsche, or Scooby should reduce the gravity effect.

there's noth8ng to stop making twin overhead crankshafts though to vary the inlet and exhaust timing. this is a development model after all and ease of manufc=acture on his lathe must have accounted for the single upper crank design? synthetic oils dont burn like old mineral oils so no HC issues, anyway there are total seal rings which would eliminate 99% of ring by-pass. looks great to challenge accepted engine design .. he's a winner already in my book

Synthetic oil does burn at in-cylinder combustion temperatures/pressures. What people mean when they say it doesnt burn is that the oil breaks down at higher temperatures so you can have hotter oil in the engine without ruinning it. Usefull in turbo cars mainly.

I'm not sure what the point of this engine is really, he's made all the usual claims (less emmissions better fuel economy, cheaper etc.) but I cant see evidence to back any of them up. My major problems with it would be extra blow-by past the extra piston rings, oil ingress unless horizontal and the wierd shape of the combustion chamber. Getting good mixing would be very difficult in a diesel engine. There is a large wall area so bad thermodynamic losses and lots of crevices and corners to trap fuel in which is very bad for HC emissions.

Hmmm, it's a cool innovation, but with the top end connected too, it's alot more inertia added to the engine. Couldn't have a high-revving engine at all.

I see this as probably handy on a big plant engine, power generators and other such uses, where weight is not an issue, but efficiency is! In a car it's just too heavy and has too much inertia imho.

Lotus toyed with having electronic valve control, which could be the next step forward. Valve lift and duration are ALL variable, and there can be all kinds of safety features for piston collision etc.

Who knows anyway, I'm sure with refinement and development it could become really viable. I'm sure the Wankel type was a bit crazy looking at first, but it's pretty damn good now!

Lotus toyed with having electronic valve control, which could be the next step forward. Valve lift and duration are ALL variable, and there can be all kinds of safety features for piston collision etc.

Mmmm, piezo electric valves allowing for total lift and timing control and 'square' cam profiles. Patent the first production system and you'll be able to pay bill gates to mow your lawn for you.

I can see problems with the tall engine dimensions causing car design problems, but if it were flipped on it's side then it should be OK.

If the power outputs are increased significantly the weight issue would be negated by being able to put a smaller size engine in to start with, if it could be turbo'd reliably I can imagine that a 4.0 V8 could easily be replaced with an engine of around 1.5 litres and produce the same power and Torque.

- relative inlet and exhaust 'piston' timing cannot be varied as they run from the same overhead crank.

thats enough to kill the idea stone dead as a way of moving forward no ?

Doesn't kill the idea. Before the advent of VVC/VTEC type cleverness, inlet and exhaust valve overlaps were fixed. It just limits the design refinement possibilities, unless the concept evolves to DOHC (with the 'C' being a crank!).

As someone else pointed out, the oil seal issues may be improved by putting the engine in a boxer configuration.

Personally I don't think it'll get developed much further - it all just looks too heavy and cumbersome for what is not, as far as I can see, a radical improvement on the current internal combustion engine design. Now if he could make it run on water....